Power over data line (PODL) board design method to improve data channel performance

ABSTRACT

Aspects of the disclosure provide for a system for a power over data line (PoDL) system. The system includes a ground plane that has a cutout. In addition, an alternating current (AC) capacitor pad configured to establish a bidirectional data channel. The AC capacitor pad is positioned in the cutout of the ground plane. Similarly, a PoDL pad connected to one or more inductors and a direct current (DC) power source is positioned in the cutout of the ground plane and is in series with the AC capacitor pad.

BACKGROUND

Data and power may be transmitted along the same line in power over datalines (PoDLs). PoDLs are sometimes used in various computerapplications, such as server computing systems, vehicle control systems,imaging systems, etc. to minimize wiring and reduce costs. In someinstances, PoDLs may include a full duplex, or bi-directional, datachannel and a direct current (DC) power channel.

BRIEF SUMMARY

Aspects of the disclosure provide for a system. The system includes aground plane, an alternating current (AC) capacitor pad, and a PoDL pad.The ground plane includes a cutout. The AC capacitor pad is configuredto establish a bi-directional data channel and is positioned in thecutout of the ground plane. The PoDL pad is connected to a plurality ofinductors and a DC power source. In addition, the PoDL pad is positionedin the cutout of the ground plane and is in series with the AC capacitorpad.

In one example, the system also includes the DC power source. The systemalso optionally includes a cable connecting the AC capacitor pad and thePoDL pad in series. In this example, the cutout of the ground plane islocated between a first end of the cable and a second end of the cable.Also in this example, the system can also includes one or more computingdevices at the first end of the cable, where the one or more computingdevices are configured to transmit data at a rate of 4 Gbps or greateralong the bi-directional data channel. The one or more computingdevices, in some implementations, are a serializer.

The system that includes the cable and the cutout also optionallyincludes one or more computing devices at the second end of the cable.In this example, the one or more computing devices are configured toprocess data received via the bi-directional data channel. Also in thisexample, the one or more computing devices are a deserializer. In otherimplementations of the system that includes the cable and the cutout,the cutout optionally has a size wherein an impedance at the ACcapacitor pad and the PoDL pad within the cutout match or closely matchan impedance at a point of the cable that is between the first end ofthe cable and the cutout.

In another example, the cutout has a size wherein an impedance at the ACcapacitor pad and the PoDL pad within the cutout match or closely matchan impedance at a point of the cable that is between the cut out and thesecond end of the cable. The system additionally or alternativelyincludes a camera system configured to collect an image and transmit theimage via the AC capacitor pad. In this example, the system alsoincludes a vehicle, and wherein the camera system is mounted on thevehicle. The system optionally includes a lidar system configured tocollect location information and transmit the location information viathe AC capacitor pad. The system in this example optionally alsoincludes a vehicle, where the lidar system is mounted on the vehicle. Inyet another example, the system also includes a layer beneath the groundplane, wherein the AC capacitor pad and the PoDL pad are positioned onthe layer within the cutout of the ground plane.

Other aspects of the disclosure provide for a method of manufacturing.The method of manufacturing includes forming a cutout in a ground plane,positioning in the cutout an AC capacitor pad configured to establish abi-directional data channel, and positioning, in the cutout, a PoDL padin series with the AC capacitor pad on a cable and in connection with aplurality of inductors and a DC power source.

In one example, the method also includes connecting a first end of thecable to a first computing device and a second end of the cable to asecond computing device. In this example, the cutout is positionedbetween the first end and the second end of the cable. The firstcomputing device in this example is optionally a serializer, and thesecond computing device in this example is optionally a deserializer.Additionally or alternatively, the cutout has a size wherein animpedance at the AC capacitor pad and the PoDL pad within the cutoutmatch or closely match an impedance at a point of the cable that isbetween the first end of the cable and the cutout. In another example,the cutout has a size wherein an impedance at the AC capacitor pad andthe PoDL pad within the cutout match or closely match an impedance at apoint of the cable that is between the cutout and the second end of thecable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial diagram of an example PoDL system 100 inaccordance with aspects of the disclosure.

FIG. 2 is a functional diagram of a communication system 200 inaccordance with aspects of the disclosure.

FIG. 3 is a functional diagram of a system 300 in accordance withaspects of the disclosure.

FIG. 4 is a pictorial diagram of a system 300 in accordance with aspectsof the disclosure.

FIG. 5 is an example flow diagram 500 in accordance with aspects of thedisclosure.

DETAILED DESCRIPTION

Overview

The technology relates to PoDL system for full duplex application. Afull duplex application is one in which data may be transmittedbi-directionally between two locations and may be useful fortransmitting large amounts of data between devices at high speeds. As anexample, a mobile image capture device may include one or more camerasmounted on a vehicle, such as a passenger car, which draw power from apower source of the vehicle using a PoDL. In this case, the PoDLconfigured for full duplex application may also be used to transmithigh-resolution images collected by the mobile image capture device toanother device for storage and/or processing in real time. Otherapplications related to vehicles including, for instance, autonomousvehicles, may include a radar or lidar sensor sending data over the PoDLto a processing device as well as a user interface computing devicesending multimedia data over the PoDL to the display monitor forpassengers.

As an example, a PoDL system may include a cable that carries a powerchannel and a data channel. The cable provides the power and data linein the PoDL system. A first pad may be positioned along the cable and ona first physical layer. Additionally, a second pad may be positionedalong the cable in series with the first pad and on a same physicallayer as the first pad. There may be a cutout in a second physical layerthat is on a side of the first physical layer opposite the side on whichthe first pad and/or the second pad are positioned. This cutout mayadjust the impedance at the first pad and/or the second pad to be closerto the impedance before and after the first pad and/or the second pad.

The features described herein may provide a circuit that provides lowimpedance at for non-alternating currents, but a higher impedance foralternating currents. Furthermore, the circuit may reduceelectromagnetic interference and, as a result, may meet the data channelelectrical specifications, such as return loss, insertion loss, andcrosstalk. The circuit may therefore be used to reduce wiring in systemsused for transferring larger amounts of data at a high rate, such as 4Gbps. The reduced wiring in these systems may significantly simplify thewiring required and allow for more freedom of movement in sensor systemswhich involves sensors which may be in motion while collecting andtransmitting data.

Example Systems

FIG. 1 shows an example PoDL system 100. The PoDL system 100 includes acable 102 that carries a power channel and a bi-directional datachannel. The cable may be a coaxial cable, and may be configured tocarry DC power and to form a bi-directional link, such as an FPD-link.For example, the bi-directional link may have a 4 Gbps forward channeland a 25 MHz backwards channel. The cable has a first end 101 and asecond end 103. The first end 101 may be connected to a first device,and the second end 103 may be connected to a second device, as describedfurther below.

Positioned between the first end 101 and the second end 103 along thecable 102 and on a first physical layer 104 is a first pad 106. Thefirst pad has a first volume. In some examples, the first volume of thefirst pad 106 comprises a rectangle-shaped face and height. The firstphysical layer 104 may be a surface layer of a printed circuit board.The surface layer may be an outermost surface of the printed circuitboard that includes portions that are of electrically conductivematerial, such as copper. The portions of electrically conductivematerial may form pads and traces.

The first pad 106 may be a PoDL pad, or a stub, that is connected to aDC power source 108 and configured to transmit power from the DC powersource along the power channel. The DC power source 108 may beconfigured to provide, for example, 48V of DC power. In someimplementations, the DC power source 108 may be a battery, a fuel cell,an alternator, a generator, or a combination of two or more of these.For example, the DC power source 108 may be both an alternator and abattery of a vehicle, where the PoDL may be configured to utilize thealternator of the vehicle as the DC power source when the vehicle'sengine is running and the battery of the vehicle as the DC power sourcewhen the vehicle's engine is not running.

To provide low impedance for the power channel and high impedance forthe data channel, one or more circuitry elements 110 may be connectedbetween the first pad and the DC power source. These one or morecircuitry elements 110 may be one or more inductors, one or more ferritebeads, or both.

A second pad 112 may be positioned along the cable 102, in series withthe first pad 106, and on the same first physical layer 104 as the firstpad 106. The second pad 112 may have a second volume larger than thefirst volume. In some examples, the second pad 112 has a largerrectangle-shaped face than and a same or similar height as the first pad106. The second pad 112 is an alternating current (AC) capacitor padthat is configured to transmit and receive data on an AC signal alongthe data channel. When the first pad 106 and the second pad 112 arelinked in series on the same first physical layer 104, there may be asmaller discontinuity at the first pad 106 than when the first pad 106and the second pad 112 are on two different layers that are connected bya via.

As shown in FIG. 1, a second physical layer 114 may be positioned on oneside of the first physical layer 104 opposite of a side on which thefirst pad 106 and the second pad 112 are placed or underneath the firstphysical layer 104. The second physical layer 114 may be a ground plane.The ground plane may be an electrically conductive surface, such ascopper, that is connected to an electrical ground. One or more points onthe first physical layer 104 may be connected to the second physicallayer 114 to allow current to flow from the first physical layer 104 tothe second physical layer 114.

As further shown in FIG. 1, there is a cutout 116 in the second physicallayer 114. The first pad 106 and/or the second pad 112 may be positionedover the cutout 116 such that the first pad 106 and/or the second pad112 are within an area covered by the cutout.

The size of the cutout 116 may be determined based on the impedancebefore and after the first and second pads 106, 112. As shown in FIG. 1,a first location 118 that is between the first end 101 of the cable 102and the cutout 116 may be before the first and second pads 106, 112, anda second location 120 that is between the cutout 116 and the second end103 of the cable 102 may be after the first and second pads 106, 112.For example, the size of the cutout 116 may be determined such that animpedance at the circuitry elements within the cutout 116, such as thefirst or second pads, matches or closely matches an impedance before andafter the cutout. For example, the impedance at the circuitry may bewithin +/−2% of the impedance before and after the cutout wherepossible, or in some cases within greater than +/−2% of the impedancebefore and after the cutout wherein possible. In addition, the size ofthe first pad or the second pad may be used to estimate the impedance ateach pad, respectively. As such, when the impedance before and after thecutout is, for example, 50 ohms, the size of the cutout may bedetermined such that the impedance at the first and second pads 106, 112is at or close to 50 ohms, such as 48 or 49 ohms.

One or more PoDL systems may be included in a communication system toconnect two computing devices via the data channel. Data received from afirst computing device may be transmitted to a second computing devicealong the data channel, as well as from the second computing device tothe first computing device, while DC power from a DC power source istransmitted along the power channel FIG. 2 shows a communication system200 that includes two PoDL systems 100 a, 100 b. PoDL system 100 a isconnected to a serializer 210, and PoDL system 100 b is connected to adeserializer 230. PoDL system 100 b may include the DC power source 108,as shown in FIG. 1, while PoDL system 100 a may not include the DC powersource. In some examples, the PoDL system 100 a may include a storagecell, such as a battery, configured to store energy received from the DCpower source 108 of the PoDL system 100 b. The cable 102 connects theserializer 210, the PoDL system 100 a, the PoDL system 100 b, and thedeserializer 230 in sequence.

The serializer 210 may be a computing device that is configured toconvert an object, such as an image, into a data stream. In someimplementations, the serializer 210 may be part of a sensing device ormay be configured to communicate with a sensing device, such as acamera. As shown in FIG. 2, the serializer 210 may include one or moreprocessors 212, a memory 214, a transmitter 220, and a receiver 222. Thesensing device may alternatively be or include one or more other typesof sensors, such as lidar, radar, or sonar.

The one or more processors 212 may be any conventional processors, suchas commercially available CPUs. Alternatively, the one or moreprocessors may be a dedicated device such as an application specificintegrated circuit (ASIC) or other hardware-based processor, such as afield programmable gate array (FPGA). Although FIG. 2 functionallyillustrates the one or more processors 212 and memory 214 as beingwithin the same block, it will be understood that the one or moreprocessors 212 and memory 214 may actually comprise multiple processorsand memories that may or may not be stored within the same physicalhousing. Accordingly, references to a processor or computer or computingdevice will be understood to include references to a collection ofprocessors or computers or memories that may or may not operate inparallel.

Memory 214 stores information accessible by the one or more processors212, including data 216, and instructions 218 that may be executed bythe one or more processors 212. Information that may be stored at thememory 214 includes data received via the PoDL system 100 a that isconnected to the serializer 210. The memory 214 may be of any typecapable of storing information accessible by the processor, including acomputer-readable medium such as a hard-drive, memory card, ROM, RAM,DVD or other optical disks, as well as other write-capable and read-onlymemories. The system and method may include different combinations ofthe foregoing, whereby different portions of the data 216 andinstructions 218 are stored on different types of media.

Data 216 may be retrieved, stored or modified by the one or moreprocessors 212 in accordance with the instructions 218. For instance,although the system and method is not limited by any particular datastructure, the data 216 may be stored in computer registers, in arelational database as a table having a plurality of different fieldsand records, XML documents or flat files. The data 216 may also beformatted in any computer-readable format such as, but not limited to,binary values or Unicode. By further way of example only, image data maybe stored as bitmaps comprised of grids of pixels that are stored inaccordance with formats that are compressed or uncompressed, lossless(e.g., BMP) or lossy (e.g., JPEG), and bitmap or vector-based (e.g.,SVG), as well as computer instructions for drawing graphics. The data216 may comprise any information sufficient to identify the relevantinformation, such as numbers, descriptive text, proprietary codes,references to data stored in other areas of the same memory or differentmemories (including other network locations) or information that is usedby a function to calculate the relevant data.

The instructions 218 may be any set of instructions to be executeddirectly (such as machine code) or indirectly (such as scripts) by theone or more processors 212. For example, the instructions 218 may bestored as computer code on the computer-readable medium. In that regard,the terms “instructions” and “programs” may be used interchangeablyherein. The instructions 218 may be stored in object code format fordirect processing by the one or more processors 212, or in any othercomputer language including scripts or collections of independent sourcecode modules that are interpreted on demand or compiled in advance.Functions, methods and routines of the instructions 218 are explained inmore detail below.

The one or more processors 212 may also be in communication with thetransmitter 220 and the receiver 222. Transmitter 220 and receiver 222may be part of a transceiver arrangement in the serializer 210. The oneor more processors 212 may therefore be configured to transmit, via thetransmitter 220, data in a signal along cable 102, and also may beconfigured to receive, via the receiver 222, data in a signal alongcable 102. Received signal may be processed by the one or moreprocessors 212 to extract the data. In some implementations thetransmitter 220 may also be configured to transmit data to anothercomputing device via another cable or a wireless network.

Deserializer 230 may be configured to receive a data stream andreconstruct an object from the data stream. Once the object isreconstructed, the deserializer 230 may store the object or transmit theobject to a next destination.

The deserializer 230 may be remote from the serializer 210. For example,the serializer 210 may be a part of or connected to a sensing system,such as a camera system, mounted on a top of a vehicle, such as apassenger vehicle, a truck, a bicycle, etc., and the deserializer 230may be in the interior of the vehicle. In some implementations, thesensing system may include one or more sensors configured to move, forinstance by rotating, relative to the vehicle in order to collect datain the environment of the vehicle. When there are one or more movingsensors in the sensing system, the first end 101 of the cable 102 may beconnected to a portion of the sensing system that is stationary, such asa central axis or an outer structure. Alternatively, the first end 101of cable 102 may be connected to a portion of the one or more sensorsthat rotate. In addition, the first end 101 may even include a rotaryjoint to allow the first end 101 to rotate with the one or more sensorswhile other portions of the cable remain more or less stationaryrelative to the one or more sensors.

The deserializer 230 may include one or more processors 232, a memory234, a transmitter 240, and a receiver 242. The one or more processors232 may be similar to the one or more processors 212 described above.Memory 234 may store information accessible by the one or moreprocessors 232, including data 236 and instructions 238 that may beexecuted by the one or more processors 232. Memory 234, data 236, andinstructions 238 may be configured similarly to memory 214, data 216,and instructions 218 described above. In addition, the deserializer 230may be configured to transmit and receive communication signals viacable 102 using the transmitter 240 and the receiver 242. Thetransmitter 240 and the receiver 242 may be configured similarly to thetransmitter 220 and the receiver 222 described above.

As shown in FIG. 3, device 310 may be a sensing device and device 320may be a storage device. The sensing device 310 may include a cameraconfigured to capture images, a radar sensor that is configured tocollect location data, a lidar sensor configured to collect locationdata, or any other type of sensor configured to collect information alocation. The information collected by the sensing device 310 may betransmitted to the serializer 210 to be converted to a data stream to besent along the cable 102 of communication system 200 to the deserializer230. The deserializer 230 may then transmit the information to thestorage device 320. In some examples, the deserializer 230 mayreconstruct the information from the data stream prior to transmittingthe information to the storage device 320.

The storage device 320 may store the information that may be retrievedor otherwise accessed by a server or client computing device forprocessing or display. As with memory 214, storage device 320 can be ofany type of computerized storage capable of storing informationaccessible by the server computing devices 310, such as a hard-drive,memory card, ROM, RAM, DVD, CD-ROM, write-capable, and read-onlymemories. In addition, storage device 320 may include a distributedstorage system where data is stored on a plurality of different storagedevices which may be physically located at the same or differentgeographic locations. Storage device 320 may be connected to the serveror client computing device via a wireless network and/or may be directlyconnected to or incorporated into any of the deserializer 230, theserver computing device, or the client computing device. The storagedevice 320 may store objects, such as images captured by the sensingdevice 310 and transmitted using the communication system 200.Information associated with images such as location information and poseinformation may be stored in association with the images.

As shown in FIG. 3, the sensing device 310, communication system 200,and storage device 320 may be included in a vehicle 330. The sensingdevice 310, with the serializer 210, may be mounted on top of thevehicle 330, and the storage device 320, with the deserializer 230, maybe positioned in the interior of the vehicle 330. As also describedabove, a battery of the vehicle 330 may be the DC power source 108 ofthe PoDL system 100 b that is connected to the deserializer 230.

In an alternative example, device 320 may be a client computing device,such as a desktop computer system, a wireless phone, or a wearablecomputing system. The client computing device may include one or moreprocessors, memory, data and instructions. Such processors, memories,data and instructions may be configured similarly to one or moreprocessors 212, memory 214, data 216, and instructions 218 of serializer210 as described above.

Example Methods

In FIG. 5, flow diagram 500 depicts a method of manufacture of some ofthe aspects described above. While FIG. 5 shows blocks in a particularorder, the order may be varied and that multiple operations may beperformed simultaneously. Also, operations may be added or omitted.

At block 502, a cutout may be formed in a physical layer of a circuitboard, such as cutout 116 in the second physical layer 114. The cutoutin the physical layer may be formed as part of the fabrication processof the circuit board. For example, when the physical layer is the groundplane, a portion of the electrically conductive surface that forms theground plane may be removed, such as by etching, in order to form thecutout before any other physical layers, such as the first physicallayer 104, masks, or finishes are added to the circuit board. The sizeof the cutout may be determined such that an impedance at the circuitryelements in proximity to the cutout, such as the first or second pads106, 112 on the first physical layer, matches or closely matches animpedance before and after the cutout. The size of the cutout may bedetermined to be at least as big as an area covered by the first and/orsecond pads, so that the first pad, the second pad, or both may fitwithin the cutout. The size may be determined to be slightly greaterthan the area, such as wider or taller by one or two millimeters or moreor less, for instance. For example, if the first and second pads coverabout a 20 millimeter by 20 millimeter area, the size of the cutout maybe 22 millimeters by 22 millimeters. Simulations may be performed todetermine the size such that the impedance at the circuitry most closelymatches the impedance before and after the cutout. In addition or in thealternative, the size of the first pad or the second pad may be used toestimate the impedance at each pad, respectively, which may be used todetermine the size of the cutout as discussed above.

At block 504, a first pad and a second pad, such as first pad 106 andsecond pad 112, may be formed in series along a cable, such as cable102, on another physical layer and at a location on the other physicallayer within the area covered by the cutout. The other physical layermay be the first physical layer 104, which may be added over the secondphysical layer 114. In some examples, the first physical layer 104 maybe copper foil overlaid on the second physical layer 114 using an epoxymaterial, such as fiberglass. The copper foil of the first physicallayer 104 may be etched to form the first pad, the second pad, and thecable. The first pad may be a PoDL pad that is connected to a DC powersource, such as DC power source 108, and the second pad may be an ACcapacitor pad. In some alternatives, only the first pad or the secondpad may be positioned within the cutout area.

At block 506, one or more circuitry elements that are designed toprovide low impedance for a non-alternating current and high impedancefor an alternating current, such as one or more circuitry elements 110,may be connected to the first pad. The one or more circuitry elementsmay include one or more inductors, one or more ferrite beads, or both.

At block 508, a first end of the cable may be connected to a firstcomputing device, and a second end of the cable may be connected to asecond computing device. The first computing device may be a serializer,such as serializer 210, and the second computing device may be adeserializer, such as deserializer 230.

Unless otherwise stated, the foregoing alternative examples are notmutually exclusive, but may be implemented in various combinations toachieve unique advantages. As these and other variations andcombinations of the features discussed above can be utilized withoutdeparting from the subject matter defined by the claims, the foregoingdescription of the embodiments should be taken by way of illustrationrather than by way of limitation of the subject matter defined by theclaims. In addition, the provision of the examples described herein, aswell as clauses phrased as “such as,” “including” and the like, shouldnot be interpreted as limiting the subject matter of the claims to thespecific examples; rather, the examples are intended to illustrate onlyone of many possible embodiments. Further, the same reference numbers indifferent drawings can identify the same or similar elements.

The invention claimed is:
 1. A system comprising: a ground planeincluding a cutout; an alternating current (AC) capacitor pad configuredto establish a bi-directional data channel, the AC capacitor pad beingpositioned in the cutout of the ground plane; and a power over data line(PoDL) pad connected to a plurality of inductors and a DC power source,the PoDL pad being positioned in the cutout of the ground plane andbeing in series with the AC capacitor pad.
 2. The system of claim 1,further comprising the DC power source.
 3. The system of claim 1,further comprising a cable connecting the AC capacitor pad and the PoDLpad in series, the cutout of the ground plane being located between afirst end of the cable and a second end of the cable.
 4. The system ofclaim 3, further comprising one or more computing devices at the firstend of the cable, the one or more computing devices being configured totransmit data at a rate of 4 Gbps or greater along the bi-directionaldata channel.
 5. The system of claim 4, wherein the one or morecomputing devices are a serializer.
 6. The system of claim 3, furthercomprising one or more computing devices at the second end of the cable,the one or more computing devices being configured to process datareceived via the bi-directional data channel.
 7. The system of claim 6,wherein the one or more computing devices are a deserializer.
 8. Thesystem of claim 3, wherein the cutout has a size wherein an impedance atthe AC capacitor pad and the PoDL pad within the cutout match or closelymatch an impedance at a point of the cable that is between the first endof the cable and the cutout.
 9. The system of claim 1, wherein thecutout has a size wherein an impedance at the AC capacitor pad and thePoDL pad within the cutout match or closely match an impedance at apoint of the cable that is between the cut out and the second end of thecable.
 10. The system of claim 1, further comprising a camera systemconfigured to collect an image and transmit the image via the ACcapacitor pad.
 11. The system of claim 10, further comprising a vehicle,and wherein the camera system is mounted on the vehicle.
 12. The systemof claim 1, further comprising a lidar system configured to collectlocation information and transmit the location information via the ACcapacitor pad.
 13. The system of claim 12, further comprising a vehicle,and where the lidar system is mounted on the vehicle.
 14. The system ofclaim 1, further comprising a layer beneath the ground plane, whereinthe AC capacitor pad and the PoDL pad are positioned on the layer withinthe cutout of the ground plane.
 15. A method of manufacturingcomprising: forming a cutout in a ground plane; positioning in thecutout an alternating current (AC) capacitor pad configured to establisha bi-directional data channel; and positioning, in the cutout, a powerover data line (PoDL) pad in series with the AC capacitor pad on a cableand in connection with a plurality of inductors and a DC power source.16. The method of claim 15, further comprising connecting a first end ofthe cable to a first computing device and a second end of the cable to asecond computing device, wherein the cutout is positioned between thefirst end and the second end of the cable.
 17. The method of claim 16,wherein the first computing device are a serializer.
 18. The method ofclaim 16, wherein the second computing device are a deserializer. 19.The method of claim 15, wherein the cutout has a size wherein animpedance at the AC capacitor pad and the PoDL pad within the cutoutmatch or closely match an impedance at a point of the cable that isbetween the first end of the cable and the cutout.
 20. The method ofclaim 15, wherein the cutout has a size wherein an impedance at the ACcapacitor pad and the PoDL pad within the cutout match or closely matchan impedance at a point of the cable that is between the cutout and thesecond end of the cable.